I have acid reflex when I do not take the Zantac my doctor sent me home with. I'm have a horrible time with any of the protein drinks I drink. They all cause me horrible stomach aches and I feel like I could throw up. Has anyone else had this same problem? I have a week left of a liquid diet and then move on to purée foods. I should also mention I have tried about 6 or 7 different types of protein drinks and they all have been doing it to me and they never bothered me before being sleeved. I can drink milk no problem. It does not matter if I mix the protein milk, water, juice, or food. Even the pre mixed ones in the bottles bother me.